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https://hdl.handle.net/20.500.12451/317

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Investigation on the mechanical properties of Nano-Al2O3 particle reinforced single lap adhesive joints using digimat mean field homogenization and finite element method
(Elsevier Ltd, 2025) Saraç, İsmail; Yıldırım, Ferdi
When the studies on particle reinforced adhesive joints are evaluated, there is a deficiency in simulation methods. Considering the diversity of particles and the variability of reinforcement ratios, obtaining the mechanical properties of particle reinforced adhesives experimentally is a costly process with a high workload. In this study, the mechanical properties of single-lap adhesive joints (SLJs) produced with pure DP460 and 4 % nano-Al2O3 reinforced DP460 epoxy composite adhesive were investigated using Digimat Mean Field Homogenization and Finite Element Method (FEM). At first, bulk and SLJs specimens were produced from composite and pure adhesives to perform experimental studies. Next, based on the experimental studies, finite element analysis (FEA) of the bulk specimens and SLJs was conducted. In the FEM, the Digimat-Mean Field (Digimat-MF) homogenization approach and Ansys structural analysis were employed together. In the first step of the simulation studies, the mechanical properties of the nano-composite adhesive were obtained using the Digimat-MF homeogenization method. In the second step, Digimat interface was created in the Ansys program and material properties were defined. In this way, the structural analysis of nano-Al2O3 reinforced bulk specimens and SLJs were accurately analyzed. In the FEA, tensile strength values of bulk specimens of pure DP460 and 4 % nano-Al2O3 reinforced DP460 epoxy adhesives were obtained. At the end of the study, experimental and simulation data were verified and compared. When the data acquired were evaluated, it was seen that the Digimat-MF homogenization approach and Ansys FEM were successfully applied to adhesive joints containing composite adhesives.
Electrochemical and Thermal Analysis of Lithium-Ion Battery Pack With Different Cell Configurations
(John Wiley and Sons Inc, 2024) Namaldı Kömürcü, Büşra; Elden, Gülşah; Çelik, Muhammet; Genç, Mustafa Serdar
The primary purpose of this research is to analyze and evaluate the effects of various discharge rates and cell configurations on the electrochemical and thermal behavior of a Li-ion battery pack that is exposed to ambient air throughout the discharge process. The three-dimensional numerical model is designed to accomplish this purpose and discusses two different cases. While the discharge rate is changed from 0.5 C to 2 C (stepping by 0.5 C) for each cell configuration considered in the first case, the numerical solutions are obtained for the various cell configurations (6S4P and 8S3P) by keeping the discharge rate constant at 1 C. The results obtained from these solutions show that the discharge rate affects a considerable amount of the battery performances and discharge times of the battery packs, activation, and ohmic losses occurring inside each battery cell. Moreover, 6S4P discharges over a longer period (about 25%) than 8S3P. While both activation and ohmic losses decrease with the increase of discharge rate, these losses remain almost constant at 0.5 C discharge rate in all analyzed conditions. As a result, having a battery pack with a long discharge time while maintaining low temperatures is useful and desired. With this in mind, while evaluating battery packs, the 6S4P battery pack looks to have the best arrangement.
The torsional characterization of 3D-Printed polylactic acid parts with alternating additive manufacturing parameters
(John Wiley and Sons Ltd, 2024) Saraç, İsmail; Horasan, Murat
Three-dimensional (3D) printed polymer parts can be subjected to torsional loads in accordance with the conditions of use. Understanding the torsional properties of 3D printed polymers depending on the printing parameters is a significant research topic in fused deposition modeling (FDM) additive manufacturing processes to be used as machine parts operating under torsional load, such as polymer parts manufactured by extrusion method. Some studies have shown that raster angle and printing speed affect the mechanical properties of 3D-printed polymers. However, tensile tests were used in most of those studies. In this study, the torsional behavior of 3D printed Polylactic acid (PLA) materials was investigated by static torsion tests, finite element analyses, and theoretical and failure analyses with respect to the printing speed and raster angle parameters. Torsion test specimens were manufactured at five different raster angles (0°, 30°, 45°, 60°, and 90°) and two different printing speeds (20 and 80 mm/s) from PLA material using the FDM additive manufacturing method. The results showed that raster angle and printing speed parameters affected the torsional load-carrying capacity of FDM-3D printed PLA parts. The best load-carrying capacity was achieved at 30° and 60° raster angles, while the lowest was measured at 0° raster angle. The torsional load-carrying capacity was significantly enhanced by 85% for specimens manufactured at the printing speed of 80 mm/s.
Thermal stress analysis of maxillary dentures with different reinforcement materials under occlusal load using finite element method
(Multidisciplinary Digital Publishing Institute (MDPI), 2024) Benli, Semih; Baş, Gökhan
The purpose of this study was to determine the effect of fiber reinforcement materials on the magnitude of stresses in a critical part of the maxillary denture base under thermal and occlusal load. Thermal stress analyses of the models were carried out using the finite element method. The models consisted of bone, soft tissue, interface gap, and maxillary dentures with and without reinforcements. A concentrated occlusal load of 230 N was applied bilaterally on the molar teeth. A 36 °C reference and 0 °C, 36 °C, and 70 °C variable ambient temperatures were applied to the models. CrCo, unidirectional and woven carbon/epoxy, unidirectional and woven glass/epoxy, and unidirectional and woven Kevlar/epoxy were used as reinforcing materials in the maxillary denture base made of PMMA (polymethyl methacrylate). Stress distributions on the maxillary denture’s midline and lateral line direction were evaluated. Maximum stresses in the incisal notch and the labial frenal notch of the maxillary denture were determined. Failure analysis of reinforcement materials used in maxillary dentures was carried out using the Tsai-Wu index criterion. The results obtained show that the thermal properties of reinforcement materials should be considered as an important criterion in their selection.
Impact of Window Opening Shapes on Wind-Driven Cross Ventilation Performance in a Generic Isolated Building: A Simulation Study
(Gazi Üniversitesi, 2024) Aktepe, Burak; Demir, Hacımurat
Both environmental concerns and sustainable development goals have led to the search for alternative energy-efficient solutions. Natural ventilation, a crucial aspect of energy-efficient building design, reduces dependence on mechanical systems and regulates indoor air quality and temperature using natural forces. It improves indoor air quality, reduces energy consumption, and lowers operating costs. This paper presents a computational fluid dynamics analysis of natural cross-ventilation in an isolated building with varying window opening geometries. u/uref showed a marked decrease in triangular geometries, while trapezoidal and reference geometries exhibited comparable declines. The airflow velocity profile revealed a U-shaped curve, with reductions observed within 0
Improvement of the Thermal Performance of PCM-Based Heat Sink Used in Electronic Cooling by Adding Nanoparticles
(Gazi Üniversitesi, 2024) Çiçek, Burcu
Recently, thanks to the technological advances, electronic devices are getting smaller in size. This causes an increase in the heat generation per unit area. This heat has to be removed from electronic devices for them to be longer-lasting, more efficient and more reliable. There are many active and passive methods designed for this objective. One of them is embedding phase change material (PCM) in the heat sink. PCM, during the phase change stage, absorbs the heat generated in the system and thus aids in keeping the temperature at a certain value. The biggest downside of PCM is its rapid conduction of heat. PCM properties can be improved by using nanoparticles. In this study, nanoparticles such as TiO2 and CuO were added to PCM and such a modified PCM is used in a finned heat sink. The thermal behavior of the PCM with addition of 1%, 2% and 5% TiO2 and CuO was investigated numerically in three dimensions. RT-28HC was used as the PCM in the study. It was shown that as the nanoparticle ratio increases, heat transfer coefficient of the PCM rises and the melting time of Nanoparticle PCM (NPPCM) is less than that of pure PCM. However, it was observed that, the melting time of PCM with CuO added is longer than that of the PCM with TiO2 added.
Computationally derived endosteal strain and strain gradients correlate with increased bone formation in an axially loaded murine tibia model
(Elsevier Ltd, 2024) Horasan, Murat; Verner, Kari A.; Yang, Haisheng; Main, Russell P.; Nauman, Eric A.
Osteoporosis is a common metabolic bone disorder characterized by low bone mass and microstructural degradation of bone tissue due to a derailed bone remodeling process. A deeper understanding of the mechanobiological phenomena that modulate the bone remodeling response to mechanical loading in a healthy bone is crucial to develop treatments. Rodent models have provided invaluable insight into the mechanobiological mechanisms regulating bone adaptation in response to dynamic mechanic stimuli. This study sheds light on these aspects by means of assessing the mechanical environment of the cortical and cancellous tissue to in vivo dynamic compressive loading within the mouse tibia using microCT-based finite element model in combination with diaphyseal strain gauge measures. Additionally, this work describes the relation between the mid-diaphyseal strains and strain gradients from the finite element analysis and bone formation measures from time-lapse in vivo tibial loading with a fluorochrome-derived histomorphometry analysis. The mouse tibial loading model demonstrated that cancellous strains were lower than those in the midshaft cortical bone. Sensitivity analyses demonstrated that the material property of cortical bone was the most significant model parameter. The computationally-modeled strains and strain gradients correlated significantly to the histologically-measured bone formation thickness at the mid-diaphyseal cross-section of the mouse tibia.
Flow and heat transfer analysis of submerged multiple synthetic jet impingement in a square channel with forced-flow
(Elsevier Ltd, 2024) Akdağ, Ünal; Akçay, Selma; Kılıç, Mustafa; Güngör, Bekir
This study experimentally and numerically investigated the flow and heat transfer of submerged multiple synthetic jet impingement in forced crossflow in a square-section channel with a constant heat flux on the bottom surface. In the forced channel flow, effects on heat transfer of six synthetic jets placed diagonally in the main flow have four different amplitudes and six different frequencies at various Reynolds numbers (6000 ? Re ? 40000) were examined. Jets were submerged vertically into the main flow and their effects on heat transfer in the turbulent regime of the main flow were analyzed. Temperature measurements were made using thermocouples placed at the channel entrances and exits on the target surface. The Nusselt numbers (Nu) were calculated using the measured temperatures. The results indicate that at Re = 6000, the target surface temperature decreases significantly with increasing amplitude and frequency, and the effects of amplitude and frequency on surface temperatures decreased at increasing Reynolds numbers. It was observed that the THP values increased with increasing amplitude and frequency for all Reynolds numbers tested. For a constant jet parameter (Ao = 0.88 and Wo = 27), the highest THP was determined as 2.06 at Re = 6000.
Design and optimization of hybrid renewable energy systems for hydrogen production at Aksaray University campus
(Institution of Chemical Engineers, 2024) Demir, Hacımurat; Demir, Hacımurat
In this study, an off-grid HRES is proposed to ensure the electricity demands of the campus in a reliable, cost-effective, and non-polluting way for Aksaray University to have a sustainable and green campus. Within this framework, three HRESs were designed and compared using HOMER Pro software to find the optimum HRES, using a combination of different components related to zero carbon emissions and fully renewable energy sources, including transportation with environmentally friendly hydrogen fuel cell buses for students, academics, and staff. According to the optimization results obtained for the various configurations, the optimum HRES has a net cost of $20.3 million for the 25-year project life, with annual costs of $1.57 million. The levelized cost of electricity of the proposed system, represented by Scenario III, is calculated to be 0.327$/kWh. The PV panels produce 4,758,497 kWh/year at a levelized cost of 0.0404$/kWh, while the wind turbines produce electricity at a levelized cost of 0.0625$/kWh. The optimal system includes a 2000 kW electrolyzer that produces 73,061 kg of hydrogen annually, with a consumption rate of 46.4 kWh/kgH2. The hydrogen tank has an energy reserve of 83,333 kWh with a storage capacity of 2500 kg. The results indicate that Scenario III is a robust, cost-effective, and environmentally friendly energy solution for the campus, paving the way for a greener future. Furthermore, the proposed HRES model provides a practical framework that can influence campus energy policies and potentially serves as a model for other educational institutions that are interested in implementing sustainable energy solutions.
Yapıştırma bağlantılarında hasar kriterlerinin incelenmesi
(Van Yüzüncü Yıl Üniversitesi, 2024) Saraç, İsmail
Yapıştırıcıların endüstriyel uygulamalarda kullanımının artmasıyla birlikte, yapıştırma bağlantılarında hasar analiz çalışmaları yapılmaya başlanmıştır. Yapılan çalışmalar, yapıştırma bağlantılı yapıların tasarımında mühendisler için önemli bilgiler sunmuş ve tasarımların şekillenmesine katkı sağlamıştır. Yapıştırma bağlantılarının mukavemetini tahmin etmeye yönelik ilk çalışmalar analitik yaklaşımlar kullanılarak yapılmıştır. Bunu takiben, Sonlu Elemanlar Yönteminin yaygınlaşmasıyla birlikte, geometri sınırlaması olmaksızın, yapıştırma bağlantılarının dayanım tahminleri kapsamlı bir şekilde yapılmaya başlanmıştır. Yapıştırıcılar için literatürde çok sayıda hasar kriteri mevcuttur. Hasar kriteri seçiminde, kullanılan yapıştırıcının sünek veya gevrek yapıda olduğunun bilinmesi önemlidir. Ayrıca, yapıştırıcı hasar kriterinin uygulanabilmesi için, yapıştırıcı tabakasının, bağlantının toplam mukavemetinin en zayıf kısmı olması gerekir. Bu çalışmada, gevrek karakterli Araldite AV138 ve sünek yapıda olan Araldite 2015 yapıştırıcılar kullanılarak oluşturulan tek tesirli bindirme bağlantılarında analitik ve sayısal yöntemler kullanılarak hasar yükleri hesaplanmıştır. Elde edilen analitik ve sayısal hasar yükleri literatürdeki bir deneysel çalışma ile karşılaştırılarak, yapıştırıcı plastik davranışının, hasar kriteri seçiminde önemi gösterilmiştir. Çalışma sonucunda, gevrek karakterli yüksek dayanımlı AV138 yapıştırıcının kullanıldığı tek tesirli yapıştırma bağlantılarında Von Mises kriterinin, sünek yapıdaki Araldite 2015 yapıştırıcının kullanıldığı tek tesirli yapıştırma bağlantılarında ise Global Akma kriterinin kullanılmasının incelenen diğer yöntemlere göre daha uygun olduğu gösterilmiştir.
Numerical investigation on thermal behaviors of Heat Sinks and Hybrid Heat Sinks with different PCMs for electronic cooling
(SAGE Publications Inc., 2024) Çiçek, Burcu
In this study, a numerical method was used to investigate the melting process of PCM-Heat Sink and PCM-Hybrid Heat sinks for electronic cooling. Firstly, three different PCMs, designated as RT-28HC, RT-31, and RT-54HC, with varying thermophysical properties, were used within aluminum finned heat sink and three-dimensional time-dependent analyses was conducted using the ANSYS Fluent software, at heat fluxes of 3.6, 4.2, and 4.8 kW/m2. To calculate the enhancement ratio in the PCM-Heat Sink, setpoint temperatures of 45°C and 60°C were selected. The results revealed that RT-54HC is the best option among them, since it produced the lowest heat sink base temperature at the end of 120 min simulation period. At last, two hybrid heat sink models, designated as HPCM1 and HPCM2 were designed and their cooling performances were analyzed at heat transfer coefficients of 5, 10, and 15 W/m K. The RT-54HC was used as the PCM for hybrid heat sinks at a heat flux of 4.8 kW/m2. It was observed that HPCM1, with heat conductivity coefficients of 10 and 15 W/m2 K were more effective than PCM-HS models for cooling. In conclusion, this study provides useful guidelines for designing heat sinks and selecting PCM types for electronic cooling.
The fatigue responses of 3D-printed polylactic acid (PLA) parts with varying raster angles and printing speeds
(John Wiley and Sons Inc, 2024) Horasan, Murat; Saraç, İsmail
In this study, the fatigue behavior of FDM-3D printed polylactic acid (PLA) materials was investigated by rotary bending fatigue tests and finite element studies with varying printing speed and raster angle parameters. Fatigue test specimens were manufactured at five different raster angles (0°, 30°, 45°, 60°, and 90°) and two different printing speeds (20 and 80 mm/s). The effect of printing speed was evaluated at high print speed variation range (20 and 80 mm/s print speeds). It was noticed that the change in raster angle affects the fatigue life very significantly. The highest fatigue life was obtained at 30° raster angle, while the lowest fatigue life was found at 90° raster angle. Increasing the printing speed from 20 to 80 mm/s decreased the fatigue life of all specimens. The derived results from the finite element analyses were consistent with the experimental results.
Energy recovery and hydrogen production potential assessment in a natural gas pressure reduction station
(Elsevier, 2024) Ermiş, Musa; Çelik, Muhammet
An energy recovery and hydrogen production potential assessment study was carried out for a pressure reduction station by integrating a turbo expander-electrolyzer system. The hydrogen and electricity production potentials were investigated based on the natural gas flow rate. For this purpose, a turbo expander-proton exchange membrane electrolyzer system was considered, using standard data of an RMS-A type PRS. The variation in energy recovery potential was calculated according to the natural gas flow rate and inlet-outlet parameters such as temperature and pressure. By using these parameters, energy balance calculations and energy profit rate were evaluated. The energy profit rate was calculated as 274 kWh for 50.000 Sm3/h volumetric flow rate. Based on real data for a PRS, the electricity and hydrogen production potential were found to be 13.654.567?kW of electricity and 1.532.325,6 Nm3 of hydrogen production with the annual natural gas flow. According to the sensitivity analysis, increasing the station inlet temperature and outlet pressure negatively affected the energy profit rate, while increasing the inlet pressure had a positive effect. The levelized cost of electricity was calculated as 0,056 $/kW, while the levelized cost of hydrogen was found to be 1,989 $/kgH2. These results indicate that energy recovery from the PRSs is feasible and an opportunity to ensure sustainability.
Experimental investigation of the heat transfer characteristics of a synthetic annular jet impingement on a flat surface
(Taylor and Francis Ltd., 2024) Akdağ, Ünal; Akçay, Selma; Ün, Necati; Danışmaz, Merdin
Annular impinging jets create a more uniform flow on the impact surface compared to circular impinging jets, allowing the surface to cool better. Additionally, periodic flow oscillations significantly increase heat transfer by reducing the thermal resistance on the surface. Therefore, this study experimentally investigated the heat transfer characteristics of a synthetic annular jet impinging on a flat surface with constant heat flux. In the experiments, the jet-target surface distance (H/D), jet Reynolds number (Rej), oscillation amplitude (Ao), and Womersley number (Wo) were changed. In contrast, the Prandtl number (Pr) and other geometric parameters were kept constant. The effects of these parameters on heat transfer were analyzed and the results were compared with continuous circular and annular impinging jets. Local temperature values on the target surface were obtained for different parameters and heat transfer from the surface was calculated. Experimental results showed that heat transfer increased with decreasing H/D ratio for all jet types. The highest heat transfer on the surface was achieved in synthetic jet flow. Heat transfer increased as the oscillation amplitude decreased.
Microchannel modification in membraneless microfluidic fuel cell to control the concentration boundary layer
(Elsevier Ltd, 2024) Çelik, Muhammet
The concentration boundary layer thickness is one of the most important parameters used to characterize the performance of membraneless microfluidic fuel cells. Low concentration boundary layer thickness leads to a high electrochemical reaction over the electrodes, improving the performance of the fuel cell. For this purpose, this paper proposes a modified microchannel which directs the fuel and the oxidant to the electrode surfaces. According to the results obtained, the amount of concentration on the cathode electrode surface and therefore the amount of current density increased with the modified microchannel. At the same point of the cathode electrode surface, the oxidant concentration in the conventional microchannel was 0.055 mol/m3, while it was 0.19 mol/m3 in the modified microchannel. Since the concentration overpotential reduced, the limiting current density was 0.372 mA/cm2 in the conventional microchannel and 0.741 mA/cm2 in the modified microchannel. Thus, the limiting current density value increased by 91.5 %.
Atık lastik tozuna uygulanan yüzey işlemleri ve atık lastik tozunun polimer/orijinal kauçuk bileşimlerinde kullanımının incelenmesi
(Niğde Ömer Halisdemir Üniversitesi, 2024) Erzincanlı, İlker; Karabörk, Fazliye
Atık taşıt lastikleri malzemesi ve miktarı bakımından son derece değerli bir atık formudur. Atık lastiklerin geri kazanımında henüz sürdürülebilir ve verimli bir teknoloji geliştirilemediği için bu atığın değerlendirilmesi konusunda araştırmacılar çeşitli uygulamalara yönelmişlerdir. Bunlar arasında atık lastik tozlarının çeşitli malzeme bileşimlerine katılarak değerlendirilmesi önemli bir yer tutmaktadır. Bu uygulamalarda atık kauçuk tozunun katıldığı malzeme ile uyumunun kauçuğun yapısı gereği yeterince sağlanamadığı, bunun sonucunda malzeme özelliklerinin olumsuz etkilendiği görülmüştür. Kauçuk tozuna uygulanacak çeşitli yüzey işlemlerinin (yüzey modifikasyonu ve yüzey devulkanizasyonu) kauçuk tozu/matris uyumunu arttırdığına yönelik araştırmalar yoğun olarak sürdürülmektedir. Bu çalışmada, kauçuk tozuna uygulanan yüzey işlemleri detaylı olarak ele alınmış ve konuyla ilgili yapılan literatür çalışmaları incelenmiştir. Yapılan araştırmalar, kauçuk tozuna uygulanan yüzey işlemlerinin, tozun içine katıldığı malzeme ile uyumunu arttırdığını ortaya koymaktadır.
Topology optimization and numerical verification in an aircraft engine bracket
(Gümüşhane Üniversitesi, 2024) Saraç, İsmail; Koçak, Alp Timuçin
The importance of saving energy and materials by lightening structures is constantly increasing. With its powerful software capabilities, Topology Optimization produces solutions for this exact purpose. In addition, thanks to Topology Optimization, more innovative and competitive structures can be produced. The development of additive manufacturing methods has also increased interest in Topology Optimization. In Topology Optimization, volumetric elements that do not carry any load or carry little load are removed from the structure. Thus, lighter, but sufficiently durable structures can be obtained. In this study, the topology optimization of a bracket used as a fastener in a jet engine was carried out using ABAQUS Finite Element software. Required bracket geometry, load conditions, and material information were obtained from an online design competition announced by General Electric. Ti6Al4V alloy was used as the bracket material. At the beginning of the study, static analysis was performed on the original bracket model to obtain the load paths required for topology optimization. As a result of the static analysis, the load paths within the jet engine bracket were determined and topology optimization was applied to the bracket to minimize the mass without reducing the rigidity. As a result of the analysis studies, it has been proven that nearly 80% material savings can be achieved from the bracket thanks to topology optimization.
Investigation of the aerodynamic effects of bio-inspired modifications on airfoil at low Reynolds number
(Universiti Malaysia Pahang, 2023) Demir, Hacı Murat; Kaya, B.
A numerical study was performed to investigate flow behaviors around bioinspired modified airfoils compared with NACA 4412 airfoil at Re=5.8x104 by solving the twodimensional, RANS equations with k-omega STT turbulence model. The obtained results reveal a rather abrupt decrease of lift at stall for the NACA 4412 airfoil in contrast to the mild stall depicted by the top-modified airfoil. As compared to the experimental results of the profiled airfoil in the literature, the characteristic behavior of the variation in the lift coefficient shows resemblance. It is seen that from the velocity distribution results, fluid flowed smoothly along the streamlined nose of NACA 4412 airfoil until alpha=4 degrees and streamlines adhered well for both airfoils at low angles (0 degrees, 2 degrees). Smaller circulation bubbles were noticed to settle in the canyons of the corrugated cross-section of the top-modified airfoil. In the wake region of the modified airfoil, there is no obvious large flow separation or circulation region at low angles of attack. However, the blue regions of the dimensionless velocity over the NACA 4412 airfoil and bottom-modified airfoil were narrower than over the top-modified airfoil. The recirculation zone over the airfoil started to enlarge, and the rolling up of the trailing-edge vortex appeared. After alpha=12 degrees, the adverse pressure gradient on the suction side of the airfoils became more intense. In the wake zones, it was seen that the circulation regions grew remarkably and became largest as the angle of attack rose to alpha=16 degrees, which pointed out increased drag forces of airfoils.
Stacked Heterogeneous Ensemble Learning Model in Mixed Convection Heat Transfer from a Vertically Oscillating Flat Plate
(Osmaniye Korkut Ata Üniversitesi, 2023) Akçay, Selma; Buyrukoglu, Selim; Akdağ, Ünal
In this study, the effects of mixed convection heat transfer from a moving vertical flat plate with an experimental and stacked heterogeneous ensemble learning approach are analyzed. In the experimental work, the effects on both natural and forced convection of dimensionless oscillation amplitude (Ao), dimensionless oscillation frequency (Wo) and Rayleigh number (Ra) are investigated. In the experiments, the vertical movement of the plate is provided by a flywheel-motor assembly. The average Nusselt numbers (Nu) on the fixed plate and the moving plate surface were obtained. Additionally, this study is focused on the prediction of heat transfer of a moving flat plate using single-based algorithms (Gradient Boosting, AdaBoost, Multilayer Per-ceptron) and a stacked heterogeneous ensemble learning model. The statistical per-formance of the single-based algorithms and the stacked ensemble model is meas-ured in the prediction of mixed convection heat transfer. The results show that the stacked-based ensemble learning model yielded the MSE = 2.01, RMSE = 1.42, MAE = 1.1 and R2 = 0.99 values. Overall, this study reveals that the proposed stacked en-semble machine learning model can be used successfully for modeling convection heat transfer of a moving plate.
Nano çinko oksit partikül katılan epoksi kaplamaların mekanik ve antikorozif özelliklerinin incelenmesi
(Uludağ Üniversitesi, 2023) Askerden, Mehmet Kubilay; Akdemir, Ahmet; Karabörk, Fazliye; Yazman, Şakir
Bu çalışmada, metal yüzeyleri korumak amacıyla kullanılan epoksi kaplamaya katılan ZnO nanopartiküllerin kaplamanın mekanik ve antikorozif özellikleri üzerindeki etkisi araştırılmıştır. Çalışma iki aşamada gerçekleştirilmiştir. İlk aşamada hem katılacak partikül miktarını belirleyerek kompozit malzemeyi üretmek hem de bu malzemenin özelliklerini belirlemek için çalışmalar yapılmıştır. Deneysel çalışmalar sonucunda epoksi matrise ağ. %0,5, 1 ve 1,5 oranlarında nano ZnO katılmasına karar verilmiştir. Bu oranlarla hazırlanan kompozit malzemelere uygulanan çekme testi sonunda en yüksek özellikler ağ. %1 ZnO nanopartikül katılan kompozit malzemede elde edilmiştir. Nanokompozitlerin diğer özelliklerini belirlemek amacıyla ayrıca; DSC, TGA, FTIR, SEM analizleri yapılmıştır. İkinci aşamada hazırlanan nanokompozitler çelik test plakaları üzerine kaplanmıştır. Kaplamaların antikorozif performansı asit çözeltisine daldırma ve tuz sisi testleri ile incelenmiştir. Korozyon testi sonuçlarına göre, en iyi sonuç %1 ZnO nanopartikül katılan kompozit kaplamada elde edilmiştir. Ayrıca kaplamaların darbe dayanımı, esnekliği ve çelik alt tabakaya yapışma özellikleri çeşitli testlerle incelenmiştir.

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